Photographic color developing process

ABSTRACT

THE FORMATION OF COLOR FOG DURING THE BLEACHING STEP OF COLOR PROCESSING, PARTICULARLY RAPID COLOR PROCESSING, IS SUSPRESSED BY INCLUDING CERTAIN SULFHYDRAZIDES IN THE BLEACH, BATH, AND PREFERABLY FURTHER ADDING A LARGE QUANTITY OF THIOSULFATE AS WELL AS A COLOR COUPLER THAT COUPLES WITH DEVELOPER OXIDATION PRODUCTS WITHOUT FORMING A DYE.

United States Patent Office PHOTOGRAPHIC COLOR DEVELOPING PROCESS Karl-Wilhelm Schranz, Opladen, and Erwin Schiin and Wolfgang Hiinicke, Leverkusen, Germany, assignors to Agfa-Gevaert Aktiengesellschaft, Leverkusen, Germany No Drawing. Filed Aug. 18, 1971, Ser. No. 172,891 Claims priority, application Germany, Aug. 20, 1970,

P 20 41 325.6 Int. Cl. G03c 5/00, 5/38, 5/44 US. C]. 96-22 6 Claims ABSTRACT OF THE DISCLOSURE The formation of color fog during the bleaching step of color processing, particularly rapid color processing, is suppressed by including certain sulfhydrazides in the bleach bath, and preferably further adding a large quantity of thiosulfate as well as a color coupler that couples with developer oxidation products without forming a dye.

This invention relates to a photographic color developing process, more particularly a rapid-processing technique, using aromatic sulfhydrazides as agents to prevent the formation of fog upon bleaching.

It is known to produce color-photographic images by color-forming development of exposed silver halide emulsion layers in the presence of suitable color couplers capable of reaction with the oxidation product of the color-forming developer substance, to form a dye image. Aromatic compounds containing primary amino groups, especially those of the p-phenylene diamine type, are normally used as color-forming developers. After color development, the photographic material has to be treated with a bleaching bath and a fixing bath, or with a bleachfixing bath, in order to remove image silver and any silver halide still present after development. The bleaching substances used are oxidizing agents which not only oxidize the image silver but also some residual color developers that are still present in the photographic emulsion after the development operation. This oxidation, in the presence of color couplers, leads to undesired formation of a dyefog of azomethine or indoquinone dye, referred to below as bleach fog.

To avoid this defect in processing, it is known to rinse the developed material rising rinsing times that are long in relation to the total processing time after development, or alternatively the material has to be pretreated with a stopping, or stopping and fixing bath, before the bleaching or bleach-fixing operation. Both these measures are obstacles to quick processing in the true sense and involve additional costs. Another method is to carry out the bleaching or bleach-fixing operation in the presence of special substances which inhibit formation of bleach fog. Examples of compounds that have been recommended for this purpose include N-hydroxymorpholine, N-amino morpholine, certain 3-pyrazolidone derivatives and certain amino-phenol derivatives; unfortunately, these compounds are relatively unstable in the bleaching or bleachfixing bath, or if they are sufficiently stable, they are not sufficiently active.

It is among the objects of the present invention to provide improved anti-foggants for the bleaching bath to prevent formation of the bleach fog.

We have now found a photographic process for making color-photographic images including color development of an image-wise-exposed color photographic material comprising at least one silver halide emulsion layer, bleaching and fixing or bleach-fixing, wherein bleaching or bleach-fixing is performed in the presence of an aro- 3,761,262 Patented Sept. 25, 1973 matic sulfhydrazide corresponding to the following formula R1 4 SO2NH-NH2 R The aforementioned substances are added to the bleaching or bleach-fixing bath in quantities of preferably from 0.5 to 10 g. per litre. It is also possible to briefly treat the developed material with an aqueous solution of the compound according to the invention before bleaching. In this instance, it is advisable to employ a relatively high concentration of the sulfhydrazides in the pretreatment bath. Useful results are obtained for example with aqueous pretreatment baths containing from 5 to 50 g. per litre of the sulfhydrazides.

The compounds used according to the invention can of course also be used in the conventional processing of color photographic materials, in which case intermediate rinsing is usually carried out between the developer bath, the bleaching bath and fixing bath, or the bleach-fixing bath. However, they can be used with particular advantage in so-called rapid-processing, which is preferably carried out at slightly elevated temperatures and in which intermediate rinsing should if possible be avoided. In such a process, a strong bleach fog is usually formed. In the presence of the substances used according to the inven tion, however, it is effectively suppressed.

The sulfhydrazides can be used with particular advantage in processing machines of low bath volume, for example table-top machines.

The bleaching baths normally used in color-photography can be used as bleaching or bleach-fixing baths. The bleaching substances are generally oxidizing agents which are able to oxidize any metallic silver present in the developed photographic material into the silver salt.

Preferred bleaching agents include ferric compounds, for example ferric chloride, potassium ferricyanide or the ferric salt of ethylene diamine tetraacetic acid.

Photographic bleach-fixing baths are baths in which bleaching oxidizing agents are combined with a solvent for silver salts, such as sodium thiosulfate or ammonium thiosulfate. Other complex-forming agents can also be present. Treatment with a bleaching and fixing bath not only oxidizes the metallic silver into the silver salt, it also subsequently dissolves the resulting silver salt from the layer as well. Bleaching and bleach-fixing baths are adequately known in photography. Reference is made for example to H. Berger, Agfacolor, 6th edition, pages 260 and 262; and E. Mutter, Die Wissenschaftliche und Angewandte Photographie, vol. IV (1967), pages 348, 352, 353 and 362.

Particularly good results are obtained with bleach-fixing baths having a high content of sodium or ammonium thiosulfate. Accordingly, the bleach fixing baths according to the invention preferably contain from 100 to 200 g. per litre of sodium or ammonium thiosulfate.

A further improvement is obtained if in addition socalled white couplers are applied in the bleach-fixing baths. White couplers are substances that are able to react with color-forming developer oxidation products without forming a dye. White couplers are known per se, for example from German patent specification No. 1,155,675. Reference is also made to the publication by W. Piischel in Mitteilungen aus den Forschungslaboratorien der Agfa- Gevaert AG, vol. IV, page 352 (1964).

The most favourable results are obtained with bleachfixing baths which, in addition to the sulfhydrazides and an increased thiosulfate content, contain from 1 to g. of a white coupler substance per litre.

The invention is illustrated by the following example:

An exposed color-photographic multi-layer material including a blue sensitive silver halide emulsion layer having a yellow color coupler, a green sensitive silver halide emulsion layer containing a magenta color coupler and a red sensitive silver halide emulsion layer with a cyan color coupler was developed for 50 seconds at 40 C. in a developer of the following composition:

6 g. of N-butyl-N-w-sulfobutyl-p-phenylene diamine, 4 g. of anhydrous sodium sulfite,

2 g. of hydroxylamine HCl,

100 g. of potassium carbonate, and

1 g. of potassium bromide,

made up to 1000 ml. with water.

The material was then squeezed and treated for 60 seconds at 40 C. with the following bleach-fixing bath:

3 g. of m-nitrophenylsulfhydrazide,

6 g. of the disodium salt of ethylene diamine tetraacetic acid,

40 g. of the ferric salt of ethylene diamine tetraacetic acid,

200 g. of ammonium thiosulfate,

4 3 g. of l-(m-sulfophenyl)-3-methyl-4-isopropyl-5-pyrazozolone, and 4 g. of anhydrous sodium sulfite,

made up to 1000 ml. with water.

The material was then washed, treated with a conventional stabilising bath and dried. The processed material showed extremely low dye-fog values which were comparable with the fog values obtainable in conventional processing, whilst a material processed in the manner described above, but using a conventional bleach-fixing bath from which the sulfhydrazide was absent, instead of the aforementioned bleach-fixing bath, showed excessively high fogging.

What is claimed is:

1. In a process for the production of color photographic images by imagewise exposure of a light-sensitive color photographic material which contains at least one silver halide emulsion layer and a color coupler, developing in a color-forming substance in the presence of said color coupler to react the color coupler with oxidation product of the color-forming substance so as to form a dye image and then treating the material with oxidizing agents to remove image silver and in which process the developed material is subjected to fixing, the improvement wherein the treatment of the exposed and developed material with the oxidizing agent is carried out in the presence of a sulfhydrazide having the formula:

in which R represents hydrogen, nitro or carboxyl and R represents hydrogen, halogen, or alkyl or alkoxy having up to three carbon atoms, the amount of sulfhydrazide being such that it reduces the formation of color fog during the bleaching.

2. The process of claim 1 wherein the bleach-fixing bath contains from -200 grams per litre of sodium or ammonium thiosulfate.

3. The process of claim 1 wherein the bleach-fixing bath contains from 1 to 5 grams per litre of a coupler that on reaction with color-forming developers form colorless products.

4. The process of claim 1 in which the bleaching is effected in a bleach-fixing bath containing from 100 to 200 grams of sodium or ammonium thiosulfate per litre and from 1 to 5 grams of a coupler that on reaction with color-forming developers form colorless products.

5. The combination of claim 1 in which the bleaching is effected with a bleach bath containing 0.5 to 10 grams of the sulfhydrazide per litre.

6. The combination of claim 1 in which the bleaching is effected without a preliminary rinse of the image.

References Cited UNITED STATES PATENTS 2,286,662 6/1942 Weyde et al. 9656 2,384,658 9/1945 Vittum 9656 3,293,036 12/1966 Meckl et al 96-60 BF FOREIGN PATENTS 6516093 2/1966 Netherlands 9666.1

NORMAN G. TORCHIN, Primary Examiner M. F. KELLEY, Assistant Examiner US. Cl. X.R.

9660 R, 60 BF, 61 R 

